Time to Digital Converters (TDC) are generally used to provide a digital output representing a timing value. A typical TDC circuit measures a time difference between two events: a start and a stop event. In its simplest form, a counter updates based on a high frequency oscillator running at a frequency f0. The counter updates once every period
      (          1              f        0              )    .The TDC circuit initiates the counter when the start event occurs. The TDC reads the state of the counter when the stop event occurs and stores the value as the stop counter value. The count value, in conjunction with the counter update rate
  (      or    ⁢                  ⁢    the    ⁢                  ⁢    period    ⁢                  ⁢          (              1                  f          0                    )        )may be used to determine the time difference between the start and stop events.